JPH09121137A - Surface acoustic wave device and equipment using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] In a surface acoustic wave device operating in a high frequency region, a surface acoustic wave device having improved pass band characteristics by blocking electromagnetic coupling between input / output terminals, particularly inside a substrate, and the same are used. Providing equipment. A conductive member 12 is arranged inside the insulating substrate 1 between the conductive pattern 5 for input terminals and the conductive pattern 6 for output terminals, and the conductive member is electrically connected to the ground pattern 7. [Effect] It is possible to prevent the electromagnetic coupling inside the substrate between the input and output terminals and realize the surface acoustic wave device having the out-of-band suppression degree (attenuation amount) of 50 dB or more in the high frequency band of 400 MHz or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device having a SAW filter and a device using the same, and in particular, it is suitable for obtaining sufficient input / output isolation in a high frequency band of 400 MHz band or more. The present invention relates to a surface wave device and a device using the same.

[0002]

2. Description of the Related Art This type of SAW filter has a possibility of exhibiting a steep cutoff characteristic with respect to a desired pass band characteristic and a possibility of being formed thin and light in a flat shape.
It can be used as an IF filter of a broadcasting receiver and a filter for mobile communication devices such as mobile phones, mobile phones and pagers. There is a strong demand for reducing the size, weight, and size of each component in this type of device. The SAW filter is an element using, for example, a 36 ° YcutX propagating LiTaO3 substrate, and is disclosed in JP-A-56-132807 and 57-202114.
No. 59-58907, especially improvements thereof.

A conventional surface mount package for SAW filters has a structure in which only a plurality of terminal patterns are provided on an insulating substrate and electromagnetic interference between them is blocked, as described in JP-A-61-245709. Is not provided.

[0004]

That is, no consideration is given to providing a shield between the input and output terminals to obtain isolation for preventing electromagnetic coupling between the input and output terminals.
Further, as shown in FIG. 8A, the SAW filter chip SF, the input / output terminals IP, O provided on the ceramic substrate P are provided.
In addition to P, it is known that at least one input side ground terminal E1 and one output side ground terminal E2 are provided, but these are not terminals for preventing electromagnetic coupling between the input and output terminals, but the back side of the substrate P. FIG. Terminal IP as 8B,
The OP extends from the front side of the substrate and is arranged opposite to the back side, so that the blocking function is insufficient. That is, each terminal on the back side functions only as a connection terminal with a peripheral circuit. Therefore, there is no problem at a low frequency of 70 MHz or less, but especially at a high frequency of 400 MHz or more, input / output isolation cannot be sufficiently obtained, and a problem occurs that the out-of-band suppression degree due to a direct wave deteriorates.

It is an object of the present invention to use a surface acoustic wave device which operates in a high frequency range and which has improved pass band characteristics by blocking electromagnetic coupling between input / output terminals, especially inside a substrate. To provide equipment.

[0006]

To achieve the above object, a surface acoustic wave device according to the present invention comprises a SAW filter chip, a conductive pattern for an input terminal electrically connected to the SAW filter chip, and In a surface acoustic wave device having an insulating substrate on which a conductive pattern for an output terminal and a ground pattern are formed, at least one is provided inside the insulating substrate between the conductive pattern for an input terminal and the conductive pattern for an output terminal. The above-mentioned conductive member is arranged, and the conductive member is electrically connected to the ground pattern.

At least one of the conductive members may be arranged on a straight line connecting the input terminal conductive pattern and the output terminal conductive pattern.

The SAW filter chip may be covered and hermetically sealed with a conductive case member. The case member may be made of metal.

Further, according to the present invention, it is possible to realize a surface acoustic wave device having an attenuation outside the pass band of 50 dB or more in a frequency band of 400 MHz or more.

[0010]

According to the present invention, since the conductive member is inserted into the insulating substrate between the input and output terminal conductive patterns and is connected to the ground pattern, the input terminal conductive pattern is changed to the output terminal conductive pattern. The direct wave transmitted through the inside of the insulating substrate can be blocked, and the electromagnetic coupling generated inside the insulating substrate can be prevented. Further, since the SAW filter chip is made of metal and covered with the cover member and hermetically sealed, it is possible to shield the electromagnetic wave from the outside.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows an embodiment of the present invention. The SAW filter chip 3 is adhered to the ceramic double-sided substrate 1 with a die bond adhesive. In addition to the conductive patterns 5 and 6 for output terminals on the substrate, the ground pattern 7 is provided in the illustrated arrangement by, for example, Au plating on the Ni plating layer. A pattern 7 is arranged so as to surround the patterns 5 and 6 provided on both sides of the center of the substrate and an insulating space 10 therebetween. The input pad 8 (for example, Al vapor deposition film) on the chip and the input terminal pattern 5 on the substrate, the output pad 9 and the output terminal pattern 6, and the ground pad and the ground pattern 7 are electrically connected by the wire 4. There is. The upper and lower surfaces of the double-sided substrate 1 are shown in FIG.
As shown in (A) and (B), the conductive patterns are provided on both sides in the same manner, and are conductively coupled to each other via the extension portions 6c and 7c provided on the side surface portions. In addition, a through hole 12 (for example, Ni is buried) may be formed and electrically connected. Central part of substrate surface (near bottom of chip 3)
By providing a plurality of through holes 12 (three in FIG. 2A) and connecting to the ground pattern 7, an effect of blocking electromagnetic coupling passing through the inside of the substrate is also produced. With the structure in which the ground pattern 7 is arranged so as to surround the input / output terminal patterns on the upper and lower surfaces of the substrate, it is possible to block direct waves due to electromagnetic coupling between the input / output terminal patterns. Thereby, the isolation between the input and the output can be sufficiently obtained even in the high frequency band of 400 MHz or more, and the SAW filter chip 3 with the out-of-band suppression degree of 40 dB or more is substantially provided.
It is possible to realize a band characteristic having steep rising and falling characteristics, which represents the acoustic characteristics of the. Then, by imposing a non-metal, for example, resin cap 2 to prevent external dust and moisture, an imposition type SAW filter device can be realized.

FIGS. 3A, 3B and 3C show another embodiment of the present invention, showing only the layout of the conductive patterns on the front, back and side surfaces of the substrate and the dimensions of the main part, and the other parts. Are omitted because they are the same as those in FIG.

The main difference between the layout of the conductive pattern of this embodiment and the layout of the conductive pattern of this embodiment is that the conductive pattern for the front and back sides of the substrate and the conductive pattern for the output terminal are provided through the extension on the side surface of the substrate. Are not connected to each other and the input and output terminal conductive patterns 35 and 36 on the front surface on which the SAW filter chip is provided are isolated, and an insulating space portion 30 is provided around them. The conductive pattern 37 for grounding is connected to the patterns 35, 36 through 30.
It is a layout that surrounds. Therefore, it is provided on the back surface of the substrate and electrically connected to the conductive patterns 35 'and 36' for the input and output terminals through the through holes 12, and the insulating space portion 30 'is provided around the conductive patterns 35' and 36 '. Is similar to the layout shown in FIG. In this way, the conductive pattern for the input and output terminals is isolated as shown in FIG.
It becomes possible to seal using a metal (conductive) cap shown by.

In the embodiment shown in FIGS. 3A, 3B and 3C, a ceramic substrate of 5 × 7 × 0.5 mm (material Al 2 O 3)
Use The pattern is plated with Ni and then plated with Au so that Al ultrasonic bonding is possible and solderability is also improved.

In FIG. 3A, the dimensions a and b are set to 0.5 mm and 0.55 mm for wire bonding. Further, the dimension c is 0.
7 mm. The widths d and e of the space between the shield pattern and the input / output pattern are important in terms of electrical characteristics. In particular, the dimension e portion forms a coplanar line and should be determined so as to have a characteristic impedance that matches the characteristic impedance of the SAW filter. Here, the impedance of the SAW filter is set to 50Ω. A
Since the permittivity εr of the l2O3 ceramic substrate is about 10, the line impedance becomes 50Ω at c / (c + 2c) = 0.4. As a result, e is 0.6 m
m. Similarly, d was set to 0.5 mm. Further, the widths f and g of the shield pattern are set as wide as possible within a range in which the position of wire bonding is not displaced and a short circuit is caused by a solder bridge or the like. f = 2.6 mm, g = 1.6 m
m. Moreover, the pitch h of the side surface pattern for soldering was set to 0.27 mm. A conductive portion that short-circuits the ground patterns on both surface portions of the substrate is also provided on the side surface portion in the length direction of the substrate.

A 450 MHz band SAW using the SAW filter according to the conventional imposition package shown in FIG. 8 and the SAW filter device according to the embodiment of FIGS. 1A and 1B.
FIG. 4 shows the characteristics of the filter in comparison.

FIG. 4 shows the SAW filter device using the conventional substrate shown in FIG. 9 and the SAW filter device according to the embodiment shown in FIG. 10 using the substrate shown in FIGS. 3A and 3B. And make a 450MHz band SAW filter,
The characteristics are compared. 450MHz band SAW
The basic design of the filter is a 36 ° Ycut which is a piezoelectric crystal substrate.
An element using an X-propagation LiTaO3 substrate, and the electrode pattern on the piezoelectric substrate is described in JP-A-56-132807.
It is designed by the design method described in 7-202114, 59-58907, etc. The chip size is 3.0 × 3.5 mm, and as shown in FIG. 9, each of the input and output bonding pads 41, 42 is one ground bonding pad 43, 44, 45, 46, 47, 48, 6
It is necessary to electrically connect to the package substrate by wire bonding of a total of eight wires. Therefore, as the conventional substrate, a 6-terminal substrate is used as shown in FIG.
IP, OP2 terminals for output, F1, F2, F for ground
Wire wiring was performed using 3, F4 and 4 terminals. FIG.
Reference numeral 0 is a device using the present invention, input / output bonding pads are connected to IP and OP, and ground pads 43 and 4 are connected.
4, 45, 46, 47 and 48 are connected to the ground pattern E. The substrate thus prepared was sealed with a cap to prepare a SAW filter device. For measuring the electrical characteristics of this apparatus, the characteristic measuring substrate shown in FIG. 11 is used. In the conventional apparatus, IP and IIP, OP and OOP, E are used.
1, E3 and EE1, E2, E4 and EE2 are connected by soldering, and in the device according to the present invention, IP and IIP, OP and OO
P, E6, E7, E8 and EE1, E3, E4, E5 and E
E2 is connected by soldering, the measurement board is connected by a 50Ω coaxial cable, and a network analyzer (for example, H
The electrical characteristics were measured using P. 8507B manufactured by P. In addition, in FIG. 11, the inductors L1 and L2 are matching coils that cancel the internal capacitance of the SAW filter. As can be seen from the characteristic graph, the out-of-band suppression of the device according to the present invention is 50 dB, which is better than the conventional device by 20 dB or more.

FIGS. 5 (A) and 5 (B) show still another embodiment of the present invention. On the ceramic substrate 1, the ground conductive pattern 57 is inserted and the output terminal conductive patterns 5'and 6 '.
The layout provided in the shape of a strip is shown between.

FIG. 6 shows a conductive pattern layout of another embodiment of the present invention. Thus, two input terminal conductive patterns 65-1 and 65-2, and output terminal conductive patterns 2
Even in the case of 66-1 and 66-2, the effect of the present invention can be obtained by providing the grounding pattern 67 between them, and the same applies to the case of two or more. FIG.
As for the electrical connection method of the upper and lower patterns of (A) and (B), the same effect can be obtained by a method other than the through hole 12 of this embodiment. According to the present invention, a SAW filter chip having a plurality of filter characteristics can be mounted in one package, and a dual SAW filter device for a BS tuner having filter characteristics of two different bandwidths can be mounted in one package to improve the characteristics. Can be improved.

FIG. 7 shows still another embodiment according to the present invention, in which a metallic frame 19 is bonded to the double-sided substrate 1 of FIG. 3 (A) by silver brazing or the like, and a metallic flat plate 20 is used, for example. It shows a structure of welding by seam welding or the like. Due to this structure, it is highly airtight against dust and moisture (eg 1x
It is possible to realize a Military standard) package of the order of 10 to 5 atm cc / sec He and to obtain a shielding effect against external electromagnetic waves.

[0021]

As described above, according to the present invention, the isolation between the input and the output can be sufficiently obtained.
It is possible to realize a surface acoustic wave device having an out-of-band suppression degree (attenuation amount) of 50 dB or more even in a high frequency band of 400 MHz or more.

[Brief description of the drawings]

FIG. 1 is a perspective view of a SAW filter device and a sealing cap according to an embodiment of the present invention.

2 is a top view showing a conductive pattern arrangement on the substrate of FIG.
Side view, bottom view.

FIG. 3 is a plan view of a conductive pattern arrangement (layout) according to a second embodiment of the present invention.

FIG. 4 is a characteristic diagram comparing the characteristics of a SAW filter device according to the present invention and a conventional device.

FIG. 5 is a perspective view of another embodiment.

FIG. 6 is a perspective view of another embodiment.

FIG. 7 is a perspective view of another embodiment.

FIG. 8 is a perspective view of a conventional example.

FIG. 9 is a perspective view of another embodiment.

FIG. 10 is a perspective view of another embodiment.

FIG. 11 is a perspective view of a substrate for measuring electrical characteristics.

[Explanation of symbols]

 1 ... Double-sided substrate, 2 ... Cap, 3 ... SAW filter chip, 4 ... Wire, 5 ... Input terminal pattern, 6 ... Output terminal pattern, 7 ... Ground pattern, 8 ... Top view, 9 ... Side view, 10 ... Bottom view , 11 ... Cross-sectional view, 12 ... Through hole, 13 ... Conventional substrate, 14 ... Characteristics according to the present invention, 15 ... Conventional characteristics, 16 ... Top view, 17 ... Side view, 18 ... Bottom view, 19 ... Metal Sex frame, 20 ... Metal flat plate.

Claims (6)

[Claims] 1. A surface acoustic wave having a SAW filter chip and an insulating substrate on which a conductive pattern for an input terminal, a conductive pattern for an output terminal, and a ground pattern electrically connected to the SAW filter chip are formed. In the device, at least one conductive member is disposed inside the insulating substrate between the input terminal conductive pattern and the output terminal conductive pattern, and the conductive member is electrically connected to the ground pattern. A surface acoustic wave device characterized in that 2. The surface acoustic wave device according to claim 1, wherein at least one of the conductive members is arranged on a straight line connecting the input terminal conductive pattern and the output terminal conductive pattern. . 3. The surface acoustic wave device according to claim 1, wherein the SAW filter chip is covered and hermetically sealed by a conductive case member. 4. The surface acoustic wave device according to claim 3, wherein the case member is made of metal. 5. A SAW filter chip, and a substrate on which a conductive pattern for an input terminal, a conductive pattern for an output terminal, and a ground pattern electrically connected to the SAW filter chip are formed. A surface acoustic wave device in which at least one or more conductive members are arranged inside the substrate between the conductive pattern for terminals and the conductive pattern for output terminals, and the conductive members are electrically connected to the ground pattern. An apparatus characterized in that the grounding pattern is grounded and used as a filter. 6. A surface acoustic wave device which is used as a filter in a frequency band of 400 MHz or more and has an attenuation amount outside its pass band of 50 dB or more.